1. Field of the Invention
This invention relates to a damping force-variable damper device for vehicles provided with a power steering device, and more particularly to a structure for rendering variable the damping force of a damper in a vehicle which is provided with a power steering device having an oil passage or an oil chamber of which internal pressure increases to a high level as the steering angle becomes large; and a damper device which includes a cylinder filled therein with a working oil, and a piston fitted slidably in the cylinder to divide the interior thereof into an upper oil chamber and a lower oil chamber, the damper device being adapted to damp the relative movements of a chassis and a wheel support member.
2. Description of the Prior Art
To regulate the damping force of a damper device for vehicle in accordance with the conditions where the vehicle is used and thereby to attain a satisfactory steerability of the vehicle and riding comfort, an electronic control means is generally used in the prior art. In this art, vehicle speed, steering angle and centripetal accelration are detected electrically, and a rotary solenoid provided at an upper portion of a piston rod in the damper device is actuated in response to detected signals of such information, thereby selecting via a control rod a fixed orifice provided in a piston. In this electronic control means, however, the degree of opening of the orifice varies in a stepped manner, and the range where the variable damping force can be set is reduced. It is necessary that a vehicle speed sensor, a steering angle sensor and a centripetal acceleration sensor be provided, and that a signal-processing procedure program be input to a processor such as a microcomputer. This greatly increases the cost of manufacturing the damper device.